Thrust reverser for plug type jet engine nozzle

ABSTRACT

The specification and drawings disclose a jet engine nozzle of the type having an aerodynamically shaped plug member positioned in the nozzle outlet to define an annular outlet area. A plurality of leaves or deflector vanes are positioned in side-byside, overlapping relationship about the nozzle outlet. Means are provided for moving the leaves simultaneously between first and second positions to vary the effective area of the annular outlet. Thrust reversing means are associated with the leaves including flow diverting means which become operative as the leaves approach the second position to direct at least a portion of the exhaust gases in a direction having a component opposite to the direction of flow through the annular area. Preferably, the flow diverting means comprise vanes carried on the leaves.

United States Patent Steffen 51 Apr. 25, 1972 [54] THRUST REVERSER FOR PLUG TYPE [21] Appl. No.: 51,519

[52] US. Cl. ..239/265.39

3,500,645 3/1970 Hom ..239/265.29X 3,500,646 3/1970 Hometal. ..239/265.29X

Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Thomas C. Culp, Jr. Attorney-Fay, Sharpe and Mulholland [5 7] ABSTRACT The specification and drawings disclose a jet engine nozzle of the type having an aerodynamically shaped plug member positioned in the nozzle outlet to define an annular outlet area. A plurality of leaves or deflector vanes are positioned in side-byside, overlapping relationship about the nozzle outlet. Means are provided for moving the leaves simultaneously between first and second positions to vary the effective area of the annular outlet. Thrust reversing means are associated with the leaves including flow diverting means which become operative as the leaves approach the second position to direct at least a portion of the exhaust gases in a direction having a component opposite to the direction of flow through the annular area. Preferably, the flow diverting means comprise vanes carried on the leaves.

9 Claims, 5 Drawing Figures PATENTEBAPR 25 1922 SHEET 16F 2 INVENTOR. FRED M4 STEFFEN B Y 7 W I 'Arrofi/vfrs PATENTEDAPR 25 1912 SHEET 2 BF 2 INVENTOR. FRED W. STEFFE/V TIIRUST REVERSER FOR PLUG TYPE JET ENGINE NOZZLE This invention is directed toward the art of jet engines and, more particularly, to a mechanism for reversing or changing the direction of the thrust produced by the engine exhaust gases.

The invention is especially suited for use on jet engines having plug-type nozzles and will be described with particular reference thereto; however, the invention has broader application and could be used on engines having other types of nozzles.

Plug-type jet engine nozzles are well known and include an aerodynamically shaped plug member positioned in the nozzle outlet. The plug is arranged so that the gases are exhausted annularly about the plug. Normally, means are provided for varying the gas exit area. The means generally take the form of rigid leaves or baffles carried by the engine housing and arranged circumferentially about the plug. Power cylinders 'or the like are provided for actuating the leaves toward or away from the plug to vary the primary exhaust area.

Generally, the nozzles also include a cylindrical shroud mounted about the nozzle and arranged for longitudinal movement to vary the thrust and operational characteristics of the engine. The combination of the shroud together with the leaves for varying the exit area, permit the plug-type nozzles to function at high efficiency throughout a wide range of flight speeds from subsonic to supersonic, as well as, throughout a wide range of altitudes.

One problem with the plug-type nozzles has been the difficulty of providing them with thrust reversing mechanisms. As can be appreciated, most conventional thrust reversing mechanisms cannot easily be used because they interfere with the shroud or the leaves, or alternately, because they require complicated mounting and actuating arrangements. Additionally, even those thrust reversing mechanisms which can be used generally tend to unduly effect the external air flow about the nozzle.

The subject invention provides a thrust reversing mechanism that is particularly suited for plug-type nozzles and which requires no special mounting arrangements or the like. Mechanisms formed in accordance with the invention are readily capable of inflight thrust reversal since none of the components are exposed to high free stream dynamic pressures in the reverse thrust position. Additionally, in the retracted position, the mechanism presents no protuberances which can interfere with normal external air flow.

According to one aspect, the invention contemplates a thrust reverser for a jet engine of the type having a nozzle with a generally circular outlet through which the engine exhaust gases are directed and a plug member positioned in said outlet to provide an annular outlet flow area. Leaf members are carried about the nozzle and mounted for movement from a first position wherein they offer substantially no obstruction to flow through the outlet flow area through a series of positions to a second position wherein they cooperate to reduce the effective outlet flow area to a predetermined minimum. At least some of the leaf members include flow diverting means operative as the members approach the second position for directing at least a portion of the exhaust gases in a direction having a component opposite to the direction of fiow through the annular flow area.

More specifically, the invention contemplates that, preferably, the diverting means will comprise flow directing baffles or vanes carried in the leaf members and arranged to move into the exhaust gas stream as the vane members approach the second position. The vane members are preferably mounted within the nozzle housing and have no structure external to the housing. By having the thrust reversing baffles carried in the leaf members, they require no special mountings or the like. Additionally, there is no requirement for separate drive or actuating means for thrust reversing operation since the baffles move with the leaves.

Accordingly, a primary object of the invention is the provision of a particularly simple and effective thrust reversing arrangement for plug-type nozzles.

Another object is the provision of a thrust reversing mechanism which can be used on plug-type nozzles without substantial modification of standard plug-nozzle design.

A further object of the invention is the provision of a thrust reverser which does not require special mounting or actuating mechanisms.

Yet another object is the provision of a thrust reversing mechanism of the general type described which is capable of in-fiight thrust reversal since none of the components are exposed to high free stream dynamic pressures in the reverse thrust position.

A still further object of the invention is the provision of a thrust reverser wherein the travel of the moving parts between forward and reverse thrust positions is small thereby allowing actuation time tov be minimized.

These and other objects and advantages will become apparent from the following description when read in conjunction with the accompanying drawings wherein;

FIG. 1 is a pictorial view of the outlet nozzle end portion of a jet engine provided with a thrust reversing mechanism formed in accordance with a preferred embodiment of the invention;

FIG. 2 is a cross-sectional view taken on line 22 of FIG. 1 showing the thrust reversing mechanism in its full reversed position;

FIG. 3 is a view similar to FIG. 2 but showing the mechanism in a forward thrust position and with the shroud fully extended;

FIG. 4 is a view similar to FIG. 3 but showing the mechanism in a full forward position and the shroud in the retracted position; and,

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 4.

Referring in particular to FIGS. 1 and 2, the jet engine assembly shown includes a generally cylindrical outlet duct portion 10 which is connected to the engine proper (not shown) through a transition piece 11 and a cylindrical duct 13. A plug member 12 is positioned axially within the outlet 10 to define an annular outlet area 14. The particular shape of the plug member 12 forms no part of the invention but it will be noted that it is somewhat of a tear drop shape and is supported within the outlet duct 10 by, for example, a plurality of struts l6.

As is conventional with plug-type nozzles, a plurality of movable leaves or outlet control members 20 are positioned in side-by-side relationship continuously about the periphery of the outlet 10. As best shown in FIG. 1, the leaves 20 are in altemate overlapping relationship so that they define a circumferential outlet control baffle arrangement. The leaves are arranged for reciprocal movement along paths that are inclined relative to the nozzle axis so that they can be retracted to a position wherein the annular outlet flow area is at a maximum or extended from the housing to substantially close the flow area. In the embodiment under consideration, each of the leaves 20 is of somewhat rectangular configuration and longitudinally curved as best shown in FIG. 2. Their outer free ends 22 are preferably shaped so as to closely engage the outer surface of the plug 12 when in the fully extended position.

In the embodiment under consideration, the leaves 20 are supported from fixed brackets 24 which are rigidly joined to a cylindrical housing or support ring 26 which extends circumferentially about the outlet duct 10. As best shown in FIGS. 1

and 5, one of the support brackets 24 is associated with each of the leaves 20. A pair of rollers or the like 27 extend laterally from the side of each support bracket 24 and engage in generally U-shaped guide tracks 28 joined to the top surface of each leaf 20.

The leaves are arranged to be simultaneously actuated from a retracted position as shown in FIG. 4 to the fully extended position as shown in FIG. 1. The means for actuating the leaves could take a variety of forms; however, in the preferred embodiment, the drive means comprise a cylindrical drive ring 30 which is carried within the leaf support ring 26 and extends circumferentially about the outlet duct 10. The drive ring 30 is connected with each leaf 20 through a link 32 (see FIG. 2). Each link is pivotally connected by a pin or the like to the inner end of its respective leaf 20 and also pivoted to the ring 30. The ring 30 is driven longitudinally of the nozzle by any convenient form of linear actuator such as through the use of a plurality of fluid pistons 33 carried within the leaf support ring 26 and having their piston rods 34 drivingly connected to the unison ring 30.

As is customary with plug-type nozzles, a shroud member 36 is mounted for longitudinal sliding movement on the outer surface of the leaf support ring 26. The shroud 36 is preferably arranged so that it can be moved from a retracted position as shown in FIG. 2 to a fully extended position as shown in FIG. 3. Normally, the shroud is extended to the position shown in FIG. 3 for operation in the supersonic cruise range of engine operation. The particular manner in which the shroud is driven forms no part of the invention and has been illustrated merely to show the relationship of the shroud to the leaves and associated leaf actuating mechanism.

Of particular importance to the invention is the arrangement whereby the described nozzle structure can be provided with thrust reversing capabilities with the addition of a minimum amount of added structure and without the necessity of any special thrust reversing drive mechanism or the like. In particular, according to the subject invention, each or a substantial number of the leaves 20 are provided with flow directing baffle means that function to divert at least a portion of the gas exiting from the nozzle in a direction opposite to that required for forward thrust operation. Although the means could take many forms, in the subject embodiment, they are shown as comprising cascade box members 40 carried on the inner end portion of each leaf 20. The cascade box members 40 each comprise an outer, generally rectangular frame member 42 which is joined to the outer surface of the leaf 20. Extending transversely between the lateral sides of each frame 42 are a plurality of baffles or deflector vanes 44 inclined as best shown in FIG. 2. In the area of the cascade boxes, the leaves are cut out so that exhaust gases can pass through the leaves upwardly through the cascade boxes.

As can be appreciated, when the leaves are in a full or partially retracted position, such as shown in FIG. 3, the cascade boxes are withdrawn behind the outlet end of duct 10. Additionally, a resilient circumferential seal member 50 is provided to seal between the end of the outlet duct 10 and the inner surface of leaves 20.

However, as the leaves are actuated further out of the housing, the cascade boxes are exposed to the exhaust gas flow exiting from the duct 10 to produce a reverse thrust operation. The amount of reverse thrust produced increases as the leaves are moved still further out of the housing. When the outer free end 22 of each leaf is in engagement with the outer surface of the plug 12, substantially the entire exhaust gas flow must pass through the baffles 44 in the cascade boxes. Because of the positioning of the baffles 44, the exhaust gases are directed so as to have a major component in a direction opposite to the normal outlet direction to provide full reverse thrust.

The invention has been described in great detail sufficient to enable one of ordinary skill in the jet engine art to make and use the same. Obviously, modifications and alterations of the preferred embodiment will occur upon a reading and understanding of the specification and it is my intention to include all such modifications and alterations as part of my invention insofar as they come within the scope of the appended claims.

What is claimed is:

1. A thrust reverser for a jet engine of the type having a nozzle including a plug member defining an annular outlet through which the engine exhaust gases are directed, a plurality of leaf members carried about said nozzle and movable from a first position wherein said leaf members offer substantially no obstruction to flow through said outlet flow area through a series of positions to a second position wherein said leaf members cooperate to reduce the effective outlet flow area to a predetermined minimum, at least some of said leaf members including flow diverting means in the form of flow directing baffles rigidly mounted on said leaf members at locations such that they are exposed to gas flow only when said leaf members approach said second position to direct at least a portion of said exhaust gases in a direction having a component opposite to the direction of flow through said annular outlet flow area.

2. A thrust reverser as defined in claim 1 wherein said leaf means are mounted so that in said first position they extend generally parallel to the axis of said nozzle.

3. In a jet engine of the type having an outlet nozzle and including:

a housing having an outlet end portion through which gases from said engine are exhausted;

a plug member positioned in said outlet end portion to define, in combination with said housing, a generally annular exhaust area through which said gases must pass;

the improvement comprising leaf means positioned circumferentially about said exhaust area and including a first imperforate portion and a second portion rigidly connected thereto, said leaf means mounted for movement from a first position wherein said annular exhaust area is a maximum through a series of positions to a second position wherein said annular exhaust area is reduced to a minimum by the first portions of said leaf means; and,

thrust reversing means in the form of flow directing baffles rigidly mounted on said leaf means in said second portions such that they are exposed to gas flow only when said leaf means are at a position spaced from said first position for diverting at least a portion of said gases in a direction having a component opposite to the normal exhaust direction of said gases exiting from said annular exhaust area.

4. The thrust reverser as defined in claim 3, wherein said thrust reversing means are arranged to divert increasingly larger portions of said gases the closer said leaf means are to said second position.

5. The thrust reverser as defined in claim 3, wherein said thrust reversing means comprise gas flow diverting baffle members carried by at least some of said leaf means and exposed to said gases when said leaf means are in positions spaced from said first position.

6. The thrust reverser as defined in claim 3, wherein said leaf means are positioned completely about said housing in overlapping side-by-side relationship.

7. The thrust reverser as defined in claim 3, wherein said leaf means are mounted for movement in a direction generally toward said plug member.

8. The thrust reverser as defined in claim 3, including a shroud member positioned about said nozzle and extending about said leaf means, and power means for moving said shroud member in a direction longitudinal of said nozzle.

9. The thrust reverser as defined in claim 3, wherein said leaf means each include a plurality of said baffle means. 

1. A thrust reverser for a jet engine of the type having a nozzle including a plug member defining an annular outlet through which the engine exhaust gases are directed, a plurality of leaf members carried about said nozzle and movable from a first position wherein said leaf members offer substantially no obstruction to flow through said outlet flow area through a series of positions to a second position wherein said leaf members cooperate to reduce the effective outlet flow area to a predetermined minimum, at least some of said leaf members including flow diverting means in the form of flow directing baffles rigidly mounted on said leaf members at locations such that they are exposed to gas flow only when said leaf members approach said second position to direct at least a portion of said exhaust gases in a direction having a component opposite to the direction of flow through said annular outlet flow area.
 2. A thrust reverser as defined in claim 1 wherein said leaf means are mounted so that in said first position they extend generally parallel to the axis of said nozzle.
 3. In a jet engine of the type having an outlet nozzle and including: a housing having an outlet end portion through which gases from said engine are exhausted; a plug member positioned in said outlet end portion to define, in combination with said housing, a generally annular exhaust area through which said gases must pass; the improvement comprising leaf means positioned circumferentially about said exhaust area and including a first imperforate portion and a second portion rigidly connected thereto, said leaf means mounted for movement from a first position wherein said annular exhaust area is a maximum through a series of positions to a second position wherein said annular exhaust area is reduced to a minimum by the first portions of said leaf means; and, thrust reversing means in the form of flow directing baffles rigidly mounted on said leaf means in said second portions such that they are exposed to gas flow only when said leaf means are at a position spaced from said first position for diverting at least a portion of said gases in a direction having a component opposite to the normal exhaust direction of said gases exiting from said annular exhaust area.
 4. The thrust reverser as defined in claim 3, wherein said thrust reversing means are arranged to divert increasingly larger portions of said gases the closer said leaf means are to said second position.
 5. THe thrust reverser as defined in claim 3, wherein said thrust reversing means comprise gas flow diverting baffle members carried by at least some of said leaf means and exposed to said gases when said leaf means are in positions spaced from said first position.
 6. The thrust reverser as defined in claim 3, wherein said leaf means are positioned completely about said housing in overlapping side-by-side relationship.
 7. The thrust reverser as defined in claim 3, wherein said leaf means are mounted for movement in a direction generally toward said plug member.
 8. The thrust reverser as defined in claim 3, including a shroud member positioned about said nozzle and extending about said leaf means, and power means for moving said shroud member in a direction longitudinal of said nozzle.
 9. The thrust reverser as defined in claim 3, wherein said leaf means each include a plurality of said baffle means. 